Surveys in several urban centres of the world have shown that many schoolchildren are unaware that milk is produced by cows and cotton by plants. At the NZG city learners have the opportunity to learn more about farm animals and their role in our lives.

Environment organisations also play a role in bringing people closer to nature. Here a volunteer from the Spider Club of South Africa introduces learners to whip spiders.

Urbanised areas are mostly dominated by a few species which are well adapted to human habitats. Many of these are exotic and pose a threat to local species, such as this Common myna which has infiltrated many South African cities. The distribution range of this species is increasing to an extent that in 2000 the IUCN Species Survival Commission (IUCN) declared it among the World's 100 worst invasive species.

Children of this generation spend most of their time indoors watching television or playing computer games.

"Conservationists need to reposition themselves if they want to have any impact on the extinction crisis." - Dr Ed Stam, Ecologist, NZG

Biodiversity in the urban environment?

Dr Ed Stam, Ecologist, NZG

Currently, more than half the human population on earth lives in urban areas. Although cities occupy only a small part of the land surface (~4%), their ecological footprint extends far beyond this. Maybe even more important, though, is the effect that city life has on people's connectedness with nature.

The extinction of experience

Surveys in several urban centres of the world have shown that many schoolchildren are unaware that milk is produced by cows and cotton by plants, and they are unable to identify locally common wild animals, while they have no trouble recognising hundreds of corporate logos. This is the inevitable consequence of what the ecologist and writer Robert Pyle has termed "the extinction of experience".

There are a number of factors which contribute to this phenomenon. Firstly, in most places the urban environment is a biodiversity wasteland. Urban development presents a radical change of the landscape causing most species to be displaced due to habitat destruction. A few may be able to hang on depending on their flexibility and the extent of the habitat destruction. However, urbanised areas are mostly dominated by a few species which are well adapted to human habitats. Many of these are exotic.

Secondly, in the fast-paced metropolitan lifestyle, time has become a scarce resource and not much of it is used for exploring nature. Furthermore, compared with previous generations, children of today's generation spend more of their time indoors watching television or playing computer games.

Thirdly, there is the 'shifting baseline syndrome'. This refers to the tendency of people to measure their environment against the environment they experienced in their youth. In a situation where the quality of the environment is declining, this leads to decreasing criteria for a good environment with each generation.

According to Pyle the 'extinction of experience' can lead to a vicious cycle in which a biologically 'depauperate' environment leads to disaffection and apathy, which causes the environment to deteriorate even further. Given the resulting alienation from nature of urban dwellers, they will be poorly motivated to invest in its protection. Seeing that urbanites now form the majority of the electorate, conservation is unlikely to be a high priority of politicians either.

In view of these developments, conservationists need to reposition themselves if they want to have any impact on the extinction crisis. The traditional approach of predicting disaster and attempting to raise funds to extend the protected areas is no longer sufficient. In fact, constant reiteration of the disaster message leads to irritation, despondency, disbelief or worse, indifference. An approach which is more likely to be productive is attempting to restore the connection between urban-dwelling humans and nature by enhancing the biological diversity in their daily environment.

Conservation in an urbanised world

Such an approach would require a shift of focus from protected wild areas to people's immediate environment - the environment where they live and work. There are several benefits to biological enrichment of the human habitat. First and foremost, it will restore some of the sense of connectedness with nature, especially in those that are in some capacity involved in the enrichment process. It also has the potential to alleviate some of the despondency and apathy resulting from the continuous stream of bad news about the environment. Urban biological enrichment offers an opportunity to do something positive for biodiversity and experience the effects in one's immediate environment.

Secondly, the approach contributes directly to the conservation of biodiversity. Some successes can be mentioned here. In the UK the common frog Rana temporaria is disappearing from the countryside, but its density is increasing in urban green spaces. The same is true for the bumble bee Bombus terrestris.

Thirdly, it has been proven that urban green spaces have a positive effect on human health and wellbeing.

Key determining factors of urban biodiversity are scale, structure and the density of indigenous versus alien plant species (see Biodiversity in your backyard). On the issue of scale, most gardens, or even city parks, are too small to sustain viable populations of most species. This means that biodiversity management would have to take place at the scale of neighbourhoods to whole cities, which inevitably involves integrating private gardens into a larger plan.

Clearly, local authorities cannot dictate how private garden owners should do their gardening, but they can provide incentives. These come in two categories: top down and bottom up. Top down management uses tax incentives, subsidies or regulation to promote the desired behaviour. Although top down approaches can influence people's behaviour, the disadvantage is that they often fail to change underlying values and attitudes.

The bottom up approach is where local authorities engage with existing organisations of home owners, such as ratepayers associations or horticultural societies. The advantage of this approach is that it is more instrumental in changing people's value system. The disadvantage is that only members of the mentioned organisations are reached. What may work best is to use a combined approach.

A good indication that people can be convinced to change their gardening habits to promote biodiversity are some successful NGO initiatives in the UK and the USA. Examples are given in the box below.

Opportunities in South Africa

South Africa is replete with large-scale housing developments such as townhouse complexes, retirement villages and golf estates as well as office parks and shopping malls. For any such development there is a requirement for an Environmental Impact Assessment in which the developers have to assess what impacts a project will have on the area and indicate what mitigating measures they will take.

A small step further, but possibly with far-reaching consequences, would be to require a 'biodiversity enhancement plan' from project developers. Obviously, such a plan would have to be checked by an ecologist and regular checks will have to be done on the implementation. However, combined with certification, this can become a selling point for a project.

'Reconciliation' ecology

Conservation scientists traditionally focussed on the protection of wild natural areas and some restoration of depleted areas to their original, natural state. This has not done much for the protection of biodiversity, as species are still going extinct at an unprecedented rate. A major factor in this failure to protect species is the small surface area of the protected land.

As the American ecologist Michael Rosenzweig pointed out, this is not likely to change soon. He therefore proposed a new field in ecology which he has coined 'reconciliation ecology'. The goal of it is not so much to restore natural habitats, but rather to modify places occupied by humans so as to provide for the needs of other species as well.

Here I do not mean to say that conservationists must cease to protect nature reserves, but rather that they would do well to widen their horizon and also strategise for areas inhabited by humans. This means engaging intensively with professionals from other disciplines such as social sciences and urban planning.

Existing initiatives promoting 'wildlife friendly' gardening

NGOs

In the USA the National Audubon Society's 'Audubon at Home' project offers participants the opportunity to take the 'Healthy Yard Pledge' and commit to a number of management principles. There is also the USA National Wildlife Federation Backyard Habitat Certification Scheme, which is particularly popular and currently includes over 100 000 certified backyards.

In the UK the Royal Society for the Protection of Birds (RSPB) runs the highly successful 'Homes for Wildlife' scheme.